Photographic stripping film



June 15, 1937. R coucgH ET AL 2,083,640

PHOTOGRAPHIC STRIPPING FILM Filed Dec. 6, 1954 7 Swan/v5 [Mum/0M 5T/NESUBSTPATUM 4 NITRATE SUPPORT (/IYDROLYZED CELLULOSE ACETATE) NITPATEArms/v5 SrP/PP/Nc LAYER BAPYTA Char/Ne YEMPORARYSUPPURTK 001/51: WEIGHTPAPER) amnion HezzzyE (budmmfll welk dbfonw 1 Patented June 15, 1937rno'roomrmc s'rmrrmo FILM Henry R. Couch and John H. Folwell, Rochester,N. Y., assignors, by mesne assignments, to Eastman Kodak Company, JerseyCity, N. J.

a corporation of New Jersey Application December 6, 1934, Serial No.756,294

5 Claims.

This invention relates to a stripping film and particularly to such afilm involving an im proved adhesive layer and in which the strippedfilm may be readily applied, with either surface up, to a second supportafter removal from the first temporary support. In certain aspects, thisinvention is an improvement over the stripping film described in the U.S. patent of C. R. Fordyce and M. Salo, No. 1,973,476, granted September11, 1934.

The material is particularly intended for use in making cuts fornewspaper work where high speed is desired, although it is capable ofuse for any other purpose where stripping film is ordinarily used. Inparticular, a permanent support of a hydrolyzed cellulose ester, such asis described in the said Fordyce and Salo patent, is used having on oneside a photographic emulsion layer and on the other side a very thincellulose nitrate layer, which has better adherence to glass than thehydrolyzed ester of the permanent support. This permits the strippedfilm to be placed either side up on glass. In use in newspaper work thestripped film will be cut into the desired shape and diiierent pieces byknown methods.

of film from other points may be fitted together, either side up, tomake a composite picture. After the whole is assembled the compositepicture may be used for printing directly upon metal This is a mucheasier process than joining various pieces of original photographic filmnegatives and eliminates the necessity of rephotographing or reprintingsome objects, or negatives through the film to reverse them. Anotheradvantage is that, after a print is made, all or a part may be readilystripped from the glass and used again, or another piece substituted forit.

Reference is made to the accompanying drawing, the single figure ofwhich shows on an exaggerated scale a section of film embodying ourinvention.

The layer l is a temporary support of paper which may be water permeableor non-permeable,

usually of double weight stock such as is used for stiff unmountedphotographs or photographic post-cards. This may be previously coatedwith a glossy baryta coating la. Over this is coated a layer 2 ofadhesive material which should be.

readily soluble and free from craze or cracking when dry. We have foundthat equal parts of readily soluble glue of good quality and ofglycerine make a satisfactory layer. This is dissolved in water withpreferably about 25 to 30 parts of the above ingredients to 75 to '70parts of water and this is coated on the paper and dried, or at leastpermitted to set, before the next coating is applied. The amounts ofglue and glycerine should be of the same order, that is, the amount ofglycerine should be at least one third of the amount of glue, but theexact proportions of these and of the water are not at all critical.Salicylic acid or thymol may be used as a'preservative for the glue inthe amount of approximately one tenth of one per cent of the weight ofglue.

The methods of coating the various layers would be those common inregular photographic coating operations, the paper web being passed insuccession past known coating devices such as hoppers, or immersionrolls, and being dried or conditioned between successive operationsunder controlled air conditions.

Over the adhesive layer 2 is applied a very thin layer 3 of cellulosenitrate, applied for instance from the following solution:

Cellulose nitrate parts by weight-.. 2.5 Glyceryl boriborate do 1.25Methyl alcohol parts -90 Butyl alcohol do 40-10 this layer havingpreferably a thickness of the order of one ten thousandths to onehundred thousandths of an inch. The glyceryl boriborate renders thenitrate layer more permeable to water. Other materials having the sameeffect may be used, such as sugar, glycerine, dextrine, lactic acid,mono-acetin, di-acetin and triacetin. While it is quite possible to usea thin cellulose nitrate layer without the addition of a material toincrease its water permeability, we prefer the addition of a highboiling, water soluble material of the type mentioned which iscompatible with cellulose nitrate and increases its water permeability.There is then applied a thicker layer 4 of hydrolyzed cellulose acetate,or the equivalent, as fully described in said Fordyce and Salo patent,and there may then be applied a nitrate layer 5 similar to layer 3followed by a thin gelatin sub-layer 6 and finally the sensitiveemulsion layer 1. After passing through a drying chamber the web iswound on a, roll and subsequently cut into sheets of the desired size.

We contemplate as included within our invention such modifications andequivalents as fall within the scope of the appended claims.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is:

1. A stripping film comprising a photographic layer, a support to whichthe photographic layer is permanently attached, a temporary support anda water soluble adhesive layer between the temporary and permanentsupports comprising glycerine and readily water soluble glue, theproportions of glycerine and glue being of the same order, thepermanentv support carrying also a permanently adherent very thin layerof cellulose nitrate between itself and the adhesive layer.

2. A stripping film comprising a paper support, a soluble adhesive layercomprising a mixture of glycerine and of glue readily soluble in'waterand a stripping element detachable from the support and including awater-permeable supporting layer of hydrolyzed cellulose acetatehaving-on its outer surface a sensitive emulsion and, between theadhesive layer and cellulose acetate layer, a

very thin layer of cellulose nitrate permanently adherent to thecellulose acetate layer.

3. A stripping film comprising a photographic layer, a support to whichthe photographic layer is permanently attached, a temporary support anda water soluble adhesive layer between the temporary and permanentsupports comprising glycerine and readily water soluble glue, theproportions of glycerine and glue being of the same order, the permanentsupport carrying also a permanently adherent very thin layer ofcellulose nitrate between itself and the adhesive layer, the nitratelayer including a material increasing the water permeability of thelayer.

4. A stripping film comprising a photographic layer, a support to whichthe photographic layer is permanently attached, a temporary support anda water soluble adhesive layer between the temporary and permanentsupports comprising glycerine and readily water soluble glue, theproportions of glycerine and glue being of the same order, the permanentsupport carrying also a permanently adherent very thin layer ofcellulose nitrate between itself and the adhesive layer, the cellulosenitrate layer including a high boiling, water soluble material which iscompatible with cellulose nitrate and increases the water permeabilityof the layer.

5. A stripping film comprising a permanent support, a readily solublewater adhesive layer thereon, and a stripping element including a waterpermeable supporting layer of a hydrolyzed cellulose acetate having onits outer surface a sensitive emulsion and, between the adhesive layerand the cellulose acetate layer, a very thin layer-of cellulose nitratepermanently attached to the cellulose acetate layer and including a highboiling, water soluble material which is compatible with cellulosenitrate and increases its water permeability.

HENRY R. COUCH. JOHN H. FOLWELL.

